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CFD in Fluid Machinery Design and Optimization

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A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydraulics and Hydrodynamics".

Deadline for manuscript submissions: closed (20 July 2024) | Viewed by 19991

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Special Issue Editors

Dr. Wei Li

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Guest Editor

China National Research Center of Pumps, Jiangsu University, Zhenjiang 212013, China
Interests: design and optimization of fluid machinery; computational fluid dynamics (CFD); cavitation of pump; unsteady flow and control; flow measurements and experimental techniques

Prof. Dr. Ramesh Agarwal

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Guest Editor

Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63130, USA
Interests: CFD; reactive flows; combustion; chemical looping; carbon capture and sequestration
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Dr. Jin-Hyuk Kim

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Guest Editor

Principal Researcher, Carbon Neutral Technology R&D Department, Korea Institute of Industrial Technology (KITECH), 89 Yangdaegiro-gil, Ipjang-myeon, Seobuk-gu, Cheonan-si 31056, Chungcheongnam-do, Republic of Korea
Interests: design and optimization of fluid machinery; computational fluid dynamics (CFD); steady and unsteady numerical analyses; cavitation of hydraulic machines; flow measurements and experimental techniques
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Fluid machinery has been widely used in agriculture, hydroelectric power plants, and chemical industry, among other applications, for various transport processes of different kinds of fluids. With the rapid development of high-performance computers and advanced numerical algorithms, computational fluid dynamics (CFD) technology has become an energy- and time-saving method to design and optimize fluid machinery. It can not only predict the performance of fluid machinery, but also visualize the complex flow vortexes in the turbulence flow field and even quantify the flow-induced unsteady forces by rotating units. Additionally, demands for higher reliability, better efficiency, longer lifespan, and enhanced anti-cavitation fluid machinery require advanced optimization methods with the help of CFD technology.

Even though CFD has been applied in the design of fluid machinery and made some achievements in the research on performance and design methods, there are still great challenges ahead to enhance the performance optimization of fluid machinery and its systems. At present, wider performance range, part-load conditions, unsteady flow, flow-induced vibration, and other problems are a promising research areas around the world.

This Special Issue seeks high-quality original research focusing on the latest novel advances regarding the Design and Optimization of Fluid Machinery by means of CFD. Original research and review articles are welcome.

Potential topics include but are not limited to the following:

Design and optimization of fluid machinery;
Cavitation performance and its control;
Numerical simulation of transient flow and unsteady flow;
Flow-induced vibration in fluid machinery;
Multiphase flow;
Irrigation and drainage;
Innovative technologies for flow control.

Dr. Wei Li
Prof. Dr. Ramesh Agarwal
Dr. Jin-Hyuk Kim
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

CFD
fluid machinery
design and optimization
shock and vibration
unsteady flow
cavitation
multiphase flow

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Published Papers (8 papers)

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Research

26 pages, 8947 KiB

Open AccessArticle

Angle of Attack Characteristics of Full-Active and Semi-Active Flapping Foil Propulsors

by Lei Mei, Wenhui Yan, Junwei Zhou, Yongqi Tang and Weichao Shi

Water 2024, 16(20), 2957; https://doi.org/10.3390/w16202957 - 17 Oct 2024

Viewed by 534

Abstract

As a propulsor with a good application prospect, the flapping foil has been a hot research topic in the past decade. Although the research results of flapping foils have been very abundant, the performance-influencing mechanism of flapping foils is still not perfect, and the research considering three-dimensional (3D) effects for engineering applications is still very limited. Based on the above considerations, a systematic and parametric analysis of a small aspect ratio flapping foil is conducted to correlate the influencing factors including angle of attack (AoA) characteristics and wake vortex on the propulsive efficiency. Three-dimensional numerical analyses of full-active and semi-active flapping foils are carried out in this paper, in which the former focuses on different heave amplitudes and pitch amplitudes, and the latter concentrates on different spring stiffnesses. The analysis covers the full range of advance coefficient, which starts around 0 and ends at a thrust drop of 0. Firstly, the influence of the maximum AoA (α_max) on the efficiency and thrust coefficient of these two kinds of flapping foils is analyzed. The results show that for the small aspect ratio flapping foil in this paper, regardless of the full-active or semi-active form, the peak efficiency as high as 75% for both generally appears around α_max = 0.2 rad, while the peak thrust coefficient of 0.5 occurs near α_max = 0.3 rad. Then, by analyzing the wake flow field, it is found that the lower efficiency of larger α_max working points is mainly due to the larger vortex dissipation loss, while the lower efficiency of smaller α_max working points is mainly due to the larger friction loss of the foil surface. Furthermore, the plumpness of different AoA curves is compared and analyzed. It was found that, unlike the results of full-active flapping foils, the shape of the AoA curve of semi-active flapping foils with different spring stiffnesses is similar, and the relationship with efficiency is not strictly corresponding. This study is expected to provide guidance on both academics and industries in relevant fields. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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33 pages, 13546 KiB

Open AccessArticle

Research on the Influence of Lateral Force and Pressure Fluctuation on the Stability of a Rotary Energy Recovery Device in the Desalination System

by Tianzhuang Ye, Xinchao Hu, Kaiyuan Wang, Yunfei Qu, Jiancong Lu, Renjiang Yuan and Lei Jiao

Water 2024, 16(6), 823; https://doi.org/10.3390/w16060823 - 12 Mar 2024

Cited by 1 | Viewed by 1148

Abstract

The rotary energy recovery device (RERD) plays an important role in reverse osmosis (RO) desalination; however, few investigations on the formation and influence of lateral force on the RERD rotor have been published. The transient characteristics of lateral force and its relationship with pressure distribution and fluctuation in the clearance were analyzed via computational fluid dynamics (CFD) simulation. The clearance pressure distribution and lateral force were quantified under different working conditions. The eccentricity of the rotor, resistance torque and decrease in the rotary speed due to the lateral force were simulated and they were found to change with flow rate and pressure of high-pressure outlet (P_HO). A new rotary speed prediction method including the effect of P_HO was developed. With the increasing flow rate or P_HO, the stability of RERD declined. A design optimization direction was proposed. The variation trends of rotary speed, pressure in the clearance and its fluctuation were verified through experiment. This research provides an explanation why in practice the rotary speed decreases with increasing pressure. The conclusions obtained herein can be of great significance for future research on improving the stability and lifespan and reducing the maintenance consumption of RERD. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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20 pages, 4224 KiB

Open AccessArticle

Performance of Reynolds Averaged Navier–Stokes and Large Eddy Simulation Models in Simulating Flows in a Crossflow Ultraviolet Reactor: An Experimental Evaluation

by Shuai Zhang and Adrian Wing-Keung Law

Water 2024, 16(2), 271; https://doi.org/10.3390/w16020271 - 12 Jan 2024

Viewed by 1034

Abstract

Computational Fluid Dynamics (CFD) has been increasingly adopted as a design tool for the simulation of UV disinfection efficiency and the optimization of the configuration of a UV reactor. However, the performance of CFD with different turbulence closures may vary significantly. In the present study, an experimental evaluation was performed to assess the performance of CFD with five Reynolds Averaged Navier–Stokes (RANS) turbulence closures and three Large Eddy Simulation (LES) sub-grid scale (SGS) models. A simplified crossflow reactor with a single lamp sleeve was fabricated for the experimental measurements and numerical simulations. Overall, the superior performance of LES compared to RANS models in flow predictions within a complex configuration is demonstrated. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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19 pages, 9037 KiB

Open AccessArticle

Numerical Simulation of Axial-Flow Pump Cavitation Based on Variable Frequency Speed Regulation

by Jincheng Ye, Linwei Tan, Weidong Shi, Cheng Chen and Egbo Munachi Francis

Water 2022, 14(17), 2757; https://doi.org/10.3390/w14172757 - 4 Sep 2022

Cited by 2 | Viewed by 2045

Abstract

In order to investigate the influence of variable voltage and variable frequency (VVVF) regulation on the cavitation performance of the axial-flow pump, numerical simulation and experiments were used to analyze the cavitation performance of an axial-flow pump under different VVVF modes. The VVVF modes were uniform acceleration with constant acceleration, variable acceleration with increasing acceleration, variable acceleration with decreasing acceleration, and its corresponding deceleration scheme. Furthermore, a comprehensive performance test rig was built for the pump to carry out cavitation visualization tests which verified the accuracy of numerical simulation. For the uniform acceleration scheme with constant acceleration, the change of flow field inside the impeller was stable, the expansion rate of cavitation was slow, and the growth rate of the cavitation volume was the slowest. For the variable acceleration scheme with decreasing acceleration, the cavitation extended rapidly due to the large initial velocity. For the variable acceleration scheme with increasing acceleration, cavitation extension was the slowest. The growth rate of the cavity volume of the two variable acceleration schemes was faster than that of the uniform acceleration scheme, and the changing trend was consistent. This feature indicates that the impeller rotation speed has a significant impact on cavitation, and excessive rotation speed will rapidly extend the cavitation. By monitoring the influence of cavitation on pressure distribution under VVVF, it was shown that the three acceleration schemes all produce large pressure fluctuation. For the uniform acceleration scheme with constant acceleration, the fluctuation range of pressure was more balanced, and the pressure dropped slowly. For the acceleration scheme with higher acceleration, the pressure fluctuation amplitude increased in the late stage of acceleration and the pressure decline speed accelerated. For the acceleration scheme with decreasing acceleration, the pressure showed a downward trend with violent fluctuations in the early stage and gradually tended to be flat in the late stage. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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13 pages, 7174 KiB

Open AccessFeature PaperArticle

Research on Influence of Rotation Center Eccentricity on Radial Force of Single-Blade Centrifugal Pump

by Chuanlong Wang, Linwei Tan, Weidong Shi, Cheng Chen and Egbo Munachi Francis

Water 2022, 14(14), 2252; https://doi.org/10.3390/w14142252 - 18 Jul 2022

Cited by 5 | Viewed by 2680

Abstract

To estimate the influence of the rotation center eccentricity of the single-blade centrifugal pump impeller on the radial force on it, and to explore the effective radial force balance method, a single blade pump with a power of 2.2 kW is analyzed. The accuracy of Numerical Simulation Methods are verified by tests of external characteristics (under three rotation-speeds of 1470 r/min, 2000 r/min, and 2940 r/min) and pressure distributions. There are five models with different rotation center coordinates (model a with (0,1), model b with (−1,0), model c with (0,−1), model d with (1,0), and model e with (0,0.5)) which are analyzed. The results show that the radial force of model c and model d reduced by 8.1% and 9.8%, respectively, which means the offset of the center of the impeller to the positive direction of the x-axis and the negative direction of the y-axis can effectively reduce the radial force. At the eccentricity of the impeller (2,−2), the radial force under all operating conditions is reduced, most obviously at 1.0 Q_d, which is about 17%. The study may prove helpful to designers and pump manufacturers to find a path forward for an optimal eccentricity to minimize the radial force. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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19 pages, 8849 KiB

Open AccessArticle

Research on the Relationship between Stall Propagation and Flange Leakage of Mixed-Flow Pumps

by Dele Lu, Wei Li, Shuo Li, Leilei Ji and Yi Yang

Water 2022, 14(11), 1730; https://doi.org/10.3390/w14111730 - 28 May 2022

Cited by 2 | Viewed by 1880

Abstract

In order to explore the internal relationship between stall core propagation and flange leakage flow in the rotating stall of a mixed-flow pump, based on the k-ε turbulence model, a SIMPLEC algorithm and hexahedral structured grid are used to simulate the internal flow field of the mixed-flow pump. By setting the flange clearance as 0.2 mm, 0.5 mm and 0.8 mm, the propagation characteristics of the rotating stall and the unsteady characteristics of flange leakage flow of the mixed-flow pump under the condition of near stall are studied, and the influence of the flange clearance on the pressure fluctuation characteristics of the mixed-flow pump under the condition of near stall is analyzed. The results show that the stall core is located at the outlet of the impeller and propagates from the leading edge of the adjacent blade along the opposite direction of blade rotation to the next flow channel. The pressure gradient in the stall channel and the energy loss are large. When the flange clearance is 0.5 mm and 0.8 mm, the stall core changes from one to two, and the propagation mechanism of the stall core tends to be complex in the two adjacent flow channels. When the flange clearance is 0.8 mm, the propagation period decreases. The variation law of leakage flow is consistent with the propagation law of stall core. When the flow passage changes from stall state to non-stall state, the leakage flow also changes from one state to another, so the leakage flow can be used as a form of apparent stall. Under the condition of near stall, the pressure fluctuation curve of the adjacent monitoring points has a large phase difference consistent with the propagation period of the stall core, and has a strong pressure drop. When the flange clearance is 0.5 mm and 0.8 mm, the time domain curve of pressure fluctuation has two wave troughs in one cycle. In the near stall condition, the main frequency of the pressure fluctuation at the monitoring point is the stall frequency, and the amplitude of the main frequency at the middle of the outlet is the largest. The characteristics of flange leakage flow and pressure fluctuation can better reflect the flow situation in the pump when rotating stall occurs. The research results can provide a basis for judging whether stall occurs in the flow passage of the pump. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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16 pages, 5905 KiB

Open AccessFeature PaperArticle

Effects of Closing Times and Laws on Water Hammer in a Ball Valve Pipeline

by Yong Han, Weidong Shi, Hong Xu, Jiabin Wang and Ling Zhou

Water 2022, 14(9), 1497; https://doi.org/10.3390/w14091497 - 7 May 2022

Cited by 18 | Viewed by 5445

Abstract

Water hammers seriously endanger the stability and safety of pipeline transportation systems, and its protection mechanism has been a hotspot for research. In order to study the change of water hammer pressure caused by the ball valve under different closing laws, the computational fluid dynamics method was used to perform transient numerical simulation of the ball valve under different closing times and closing laws. The results show that the faster the valve closing speed in the early stage, the greater the water hammer pressure. The vortex core motion and pressure vibration were affected by the closing law. Extending the valve closing time can effectively reduce the maximum water hammer pressure. These findings could provide reference for water hammer protection during the closing process of the pipeline system with the ball valve. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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21 pages, 7598 KiB

Open AccessFeature PaperArticle

Vortex Dynamics Analysis of Internal Flow Field of Mixed-Flow Pump under Alford Effect

by Shuo Li, Wei Li, Leilei Ji, Weidong Shi and Ramesh K. Agarwal

Water 2021, 13(24), 3575; https://doi.org/10.3390/w13243575 - 13 Dec 2021

Cited by 4 | Viewed by 3182

Abstract

A multi-region dynamic slip method was established to study the internal flow characteristics of the mixed-flow pump under the Alford effect. The ANSYS Fluent software and the standard k-ε two-equation model were used to numerically predict the mixed-flow pump’s external characteristics and analyze the forces on the impeller and guide vane internal vortex structure and non-uniform tip gap of the mixed-flow pump at different eccentric distances. The research results show that the external characteristic results of the numerical calculation are consistent with the experimental measurement. The head error of the design flow operating point is about 5%, and the efficiency error is no more than 3%, indicating the high accuracy of numerical calculation. Eccentricity has a significant influence on the flow field in the tip area of the mixed-flow pump impeller, the distribution of vortex core in the impeller presents obvious asymmetry, the strength and distribution area of the vortex core in the small gap area of the tip increase obviously, which aggravates the flow instability and increases the energy loss. With the increase of eccentricity, the strength and number of vortex core structures in the guide vane also increase significantly, and obvious flow separation occurs near the inlet of the guide vane suction surface on the eccentric side of the impeller. The circumferential distribution of L₁ and L₂ values represents the friction pressure gap in the eccentric state, and the eccentricity has a more noticeable effect on L₁ and L₂ values at the small gap; With the increase of eccentricity, the values of vorticity moment components L₁ and L₂ increase, and the Alford moment on the impeller increases. The leading-edge region of the blade is the main part affected by the unstable torque of the flow field. With the increase of eccentricity, the impact degree of tip leakage flow deepens, and the change of the tip surface pressure is the most obvious. The impact area of tip leakage flow is mainly concentrated in the first half of the impeller channel, which has an impact on the blade inlet flow field but has little impact on the blade outlet flow field. Full article

(This article belongs to the Special Issue CFD in Fluid Machinery Design and Optimization)

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